Smelting sulfur ores.



R. FLEMING.

SMELTING SULFUR ORES.

APPLICATION FILED JUNE 20, 1903.

Patented Jan. 11,1910.

2 SHEETSSHEET 1.

In ventor: RicadF'lein Witnesses R. FLEMING.

SMELTING SULFUR ORES.

APPLICATION FILED mm: 20, 190B.

95,926, I Patented Jan. 11, 1910;

2 SHEETS-SHEET 2'.

I8 F'lgz.

H IO

With asses: Inventor".

momma FLEMING, or swnmrsco'rr, MASSACHUSETTS, ASSIGNOB a d ENERAL nnnc'rnrc company, A conrona'rrozu or NEW YORK.

SMEL'IING SULFUR OBES.

Specification of Letters Patent.

Patented Jan. 11, 1910.

Application filed June 20, 1908. Serial No. 439,521.

these ores the sulfur is burned, and thenoxious fumes which escape constitute a serious nuisance in the vicinity of the smelter. My procedure not only eliminates this nuisance, but recovers a valuable product. Other impurities, such as zinc and arsenic, are recovered with the sulfur, and are subsequently purified.

As will be hereinafter more fully described, my process is carried on in a totally inclosed furnace capable of continuous operation. It is important to carry on the smelting in an inclosed space so as to avoid escape of the vapors, and oxidation of the same. As'the walls of the furnace are made relatively thick, it possesses a high heat efficiency, which is especially desirable as the smelting is carried on while the ore is in a fused state. The heat necessar to melt the ore and maintain the same in usion during the smelting operation is generated in the interior of the furnace by means of electrical energy. This method of heating makes it possible not only to keep the ore out of communication with the atmos here but enables the highly corrosive melte mass to be confined by thick walls of refractory material.

Furthermore, the heat is generated just where it is needed, and may be readily regulated to suit the conditions of the smelting operation.

The furnace in which my process is carried out is illustrated in the accompanying drawing, of which v Figure 1 is a longitudinal section and Fig. 2 is a cross-section alon r the line 22.

The features of nove ty of myinvention will be pointed out in the appended claims.

I will first proceed to explain the construction of the furnace used in connection with my invention, and then will explain from the upper level.

layer 0 refractory brick 5. In the case of certain ores, which are basic in character, thisrefractorylining is best made of basic material, such as chromite or magnesia, as a silicious or acid lining would be ra idly attacked by the charge. The smelting 0 amber is provided at each end with electrodes 6, 7. These electrodes can be made of some metal, as copper, cast about an iron pipe through which a cooling liquid is passed when the furnace is in operation. The cooling pipe has been shown. in dotted outline in Fig. l. The cooling solution is introduced into the ducts in the electrodes through the tubes 8. The leads 9, which are bolted to the electrodes and are shown as broken off in the drawing, pass to a suitable source of current.

The smelting chamber is provided with two drains, 10 and 11, as shown in Fig. 2,

.\ Vl1lCl1 enter the chamber at different levels so as to permit the matte, or metal, to be drawn off from the lower level or the slag A series of twyers, 12, lead into the smelting chamber from each side of the furnace for the introduction of a blast into the ore, as will be later explained in connection with the description of the smelting process. The twyers are insulated from the metallic casing by an insulating bushing 12*. The ore is introduced into the vertical charging chamber I through the cup-shaped opening 13, which may be closed by raising the bell 14; by

means of a motor, or in any suitable way. The lower end of the charging chamber is provided with a reciprocating piston 15, which may be directly connected to a stem cylinder 16, as diagrammatically indicated in the drawing. This piston or plunger serves to push the ore forward into the smelting chamber 1.

The condensing chamber 2" is omewhat diagrammatically shown as consisting of a series of air-cooled coils 17- and a gas-washingchamber 18. Asmore or less solid material may condensein the anterior art of cally-opening door 20. As many of these the latter.

chambers are added as required. The end coils of the condenser are provided with drains 21, as diagrammatically indicated,

through' which condensed liquid products may be drawn off. The gas-washing chamber 18 is filled with broken brick, or some other inert material, over which water is trickling, introduced through the pipe 22. Any gases which may be produced in the furnace and which are not condensed in the coils of the condensing chamber are here absorbed by the film of water on the broken material of the chamber. The condensing chamber has been shown rokenin the central portion in order to i icate that it is to be made as large as necessary to suit the conditions. It may be water-cooled, if desired, instead of'air-cooled.

- Having now explained the construction of the furnace, I willproceedto set forth the steps of the smelting of the ore in said furnac My process may be applied to a variety of ores containing sulfur with such slight modifications of treatment as will readily suggest themselves to those; skilled in the art of metallurgy; However, for the purpose of illustration, I will explain the processin detail as applied to copper ores of the pyritic variety, although other ores, as, for example, lead sulfid or galena might have served almost equally as well for the purposes of illustration. Copper ores of this variety occur associated with iron pyrites, often with considerable amounts of They frequently contain zinc, arsenic, and other elements.

When the furnace is charged for the first time the ore may be melted independently and introduced into thefurnace in a fused state, if desired, so as to distribute it continuously to the electrodes, or a bar of metal may be placed in the bottom of the furnace from electrode to electrode to serve as a heater, and thus melt the ore which is introduced in the solid state. In either case a continuous conducting layer covering the bottom of the furnace and extending from one electrode to another is to be obtained. Inthe case of the ores above mentioned, a certain amount of silic-ious-material is introduced with the oreas a flux. This flux combines with the iron to'form a slag,,as will be later explained.- A flow of cooling liquid, as water, is then started through the electrodes and a current sent through the charge. The charge if not already melted is liquefied by theheat generated by the passage of the current. The chilled electrodes cause a certain amount of the charge to solidify on their surface, as indicated, thus protecting the electrode surface. When the temperature begins to rise, at first considerable sulfur is liberated, the iron pyrites losing one atom of sulfur according to the equation FeS FeS+ S.

Sulfur vapor passes up through the crushed ore in the charging chamber, to which it gives up-part of its heat and then passes on i into the condensing chamber or dust chamber where it is condensed. A blast of steam which may be superheated, is now introduced into the molten sulfid through the twyers 12. The steam decomposes the melted sulfids and drives out the sulfur, at the same time oxidizing the iron to form iron' oxid. When sulfid ores at an elevated temperature are treated with steam there ordinarily is formed hydrogen sulfid. However, as the temperature is gradually raised an increasing-per cent. of hydrogen sulfid is broken up into sulfur and hydrogen. In

the vicinity of the temperatures employed in the present process this decomposition is almost complete, and the result of forcing steam into the melted bath results, therefore, in the formation of a certain percentage of hydrogen sulfid, and considerable amounts of sulfur and hydrogen. If desired, a certain amount of air may be forced into the melted sulfid together with the steam in order to completely oxidize the ores and furnish a certain amount of sulfur dioxid, which will interact with the free hydrogen as well as with the hydrogen of the hydrogen sulfid. Sulfur dioxid will in-- teract with hydrogen and.v with hydrogen.

sulfid according to reactions, as given below to form sulfur and water.

SO,'+2H,S=3S+2H,O

As the reactions take place in the melted bath at high temperature they proceed rapidly. The sulfur vapor, watery vapor,

together with vapors of other substances associated with the copper, such as arsenic and zinc, are carried off and condensed in the condensing chamber. They are further urified according to well known methods. ghould there be any sulfur dioxid or possibly hydrogen sulfid which has not been decomposed it will be absorbed in chamber 18.

action of thesteam with the iron sulfid combines with the silica to form silicates of. iron.

' The'heat from the oxidation of the iron and i The ferrous oxid FeO, formed by the inter- 35 fusion, forcing steam throug to the bottom of the furnace as a matte, containing some sulfur. The slag may now be partially withdrawn and an additional charge introduced into the furnace. The

operation of blowin is repeated. When a sufficient amount 0 copper matte has accumulated in the furnace it ma either be run off to another furnace to be finally purified, or it may be separately blown with either steam, or with steam and air, in the same furnace. It is finally drawn off as metallic copper containing a small amount of im urit1es.

In t e case of lead ore, the smelting operation is carried on "in much the same way,

yielding as end products metallic lead and sulfur.

What I claim as new and desire tosecure by Letters Patent of the United States, is,

1. The rocess of treating ores containing sulfur, w ich consists in melting said ore, electrically maintaining the ore in fusion out of communication with theatmosphere, forcing steam through the ore, and cooling the resulting vapors.

2. The process of treating ores containing sulfur, W ich consists in melting said ore, electrically maintaining the ore in fusion, forcing steam and air through the ore, col- 80 lecting the resulting vapors, and cooling the same.

3. The process of treating ores containing sulfur Wh1ch consists in electrically melting and electrically maintainin the ore in the ore, collecting the resulting vapors and cooling the same.

4. The recess of treating ores containing sulfur which consists in electrically melting 40 and electrically maintaining the ore 1n fusion, forcing currents of steam and air .through the ore, collecting the resulting vapors, and condensing the same.

5 The process of treating sulfid ores WhlCll consists in electrically melting electrically maintaining the ore in fusion in an inclosed s ace, forcing steam through the ore, and con ensing the resulting vapors.

' 6. The method of recovering sulfur from a sulfid ore, which consists in melting and and electrically maintaining the ore in fusion out of communication with the atmosphere, forcing steam through said ore, and cooling the resulting vapors.

7. The method of recovering sulfur from a sulfid ore, which consists in melting and electrically maintaining the ore in fusion in an inclosed space, forcing steam and air vapors. i y 8. The rocess of treating ores containing sulfur, which consists in melting said ore, electrically maintaining the ore in a fused state out of communication with the atmosconsists in melting said ore,

through said ore, and coollng the resulting 10. The process of recovering sulfur from ore, which consists in melting said ore, electrically maintaining the ore-1n fuslon.

out of communication with the atmosphere, forcin currents of steam and air into said melted ore in such proportion that but little excess of free hydro en sulfid or sulfur dioxid will be resent 1n the resulting vapors, and cooling t iese vapors below the vaporizing tem erature of sulfur.

11. T e process of reducing copper ores containing sulfur and iron, which consists in melting said ore, adding a flux to said ore, forcin currents of steam and air into said melte ore while electrically maintainin the same in fusion, and coo ing the resu ting vapors to a temperature below the va orizing temperature of sulfur.

n witness whereof, I have hereunto set my hand this 18th da of June, 1908.

RIC ARD FLEMING. Witnesses:

HELEN ORFORD, J osnrn L ons. 

